A066759 a(n) = least multiple of n differing from a prime by at most 1, if such a multiple exists; = 0 otherwise.

1, 2, 3, 4, 5, 6, 7, 8, 18, 10, 11, 12, 13, 14, 30, 16, 17, 18, 19, 20, 42, 22, 23, 24, 100, 52, 54, 28, 29, 30, 31, 32, 66, 68, 70, 36, 37, 38, 78, 40, 41, 42, 43, 44, 90, 46, 47, 48, 98, 100, 102, 52, 53, 54, 110, 112, 114, 58, 59, 60, 61, 62, 126, 128, 130, 66, 67, 68

Offset

1,2

Comments

a(n) is nonzero for all n up to 10^4. Is it always so?

Links

Table of n, a(n) for n=1..68.

Example

9 differs by 2 from the nearest prime, but 9 * 2 = 18 differs only by 1; hence a(9) = 18.

Crossrefs

Sequence in context: A200447 A274840 A205406 * A204928 A171723 A039050

Adjacent sequences: A066756 A066757 A066758 * A066760 A066761 A066762

Keyword

nonn

Author

Joseph L. Pe, Jan 17 2002

Status

approved